Anode of vacuum electric tube devices



June 4, 1929. E. Y. ROBINSON ET AL ANODE OF VACUUM ELECTRIC TUBE DEVICES Filled April 28, 1925 VVso Patented June 4, 1929.

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ERNEST YEOIVIAN ROBINSGN', OIE' LYIVIM, AND EDWARD T01-INy EGERTONHBBARD,

OF HORSIIAM, ENG-LAND, ASSIGNORS TO METRGPOLITAN-VICKERS ELECTRICAL COMPANY LIMITED, A BRITISH COMPANY. I y

ANODE 0E VACUUM ELECTRIC TUE DEVICES.

Application led April 28, 1925, Serial No. 26,354, and in GreatBritain April 30, 1924.

'Ihis invention relates to vacuum electric tubes such as rectifiers or triodes of the type having a short gap and is more especially applicable to tubes having short gaps in which ionization is reduced to aminimum as described in the specification of co-pending application Serial No. 603,715 filed 27th November', 1922. f

The object of the invention is to provide an anode assembly whereby a short gap and a small inter-electrode space between the cathode and the anode may be easily obtained. Another object is to provide a type of anode which' is suitable for employment with lamentary cathodes which may be supported as described in the specilication of ,co-pending application Serial No. 722,811 filed 27th V,I une, 1924, and which may itself be supported in the manner described inthis specification. Another object of the invention is to provide means, when a iilament having more than one leg is employed or when a plurality of filaments are employed, whereby each filament or leg has an independ-y ent active portion of the anode, by which means its capacity for heat dissipation is increased. The lengths of the possible paths between the cathode and anode are reduced to an absolute minimum and the filament or cathode, especially when the tube is a rectifier, is not subjected to unbalanced electrostatic stresses.

According to the invention the anode assembly consists of a plurality of parallel members having one or more grooves or ducts therein, and so placed that the grooves or ducts form respectively one or more tunnels, the said tunnels forming active portions of the anodey and being so arranged that each tunnel is formed by two grooves or ducts only.l In one arrangement a plurality of tunnels are formed by -the anode assembly and furthermore in the case where a filamentary cathode is employed each tunnel preferably embraces or encircles only one filament leg. 'The tunnels are preferably substantially cylindrical;

In the preferred method of construction the anodes are pressed-out of sheet material and may be, for example, of nickel or molybdenum. lIhey are preferably supported, as described in the speciiication of co-pending application Serial No. 722,811 tiled 27th.

June, 192e, aforesaid, from framework by metallic cross pieces which preferably eno'age with the outsides of the cylindrical tunnels. In the case of molybdenum the anode portions may be stapled, riveted or welded together, while in the case of nickel they may be Welded together.

With the construction according to the invention the capacity for dissipation of heat by the anode may be raised to any amount by increasing the size and thickness of the sheets from which they are formed.

The anode may assume several forms in practice of which the following are simple examples. f i In one form the anode comprisestwo eX- actly similar rectangular sheet metal plates the length of which is several times greater than the width thereof, each plate being provided by pressing or otherwise with one longitudinal semi-circular Channel or with a plurality of parallelV semi-circular channels so disposed in the respective plates that when superposed on one another one or more longitudinal .cylindrical tunnels are provided in which a corresponding number of filaments is adapted to be disposed. In another form the anode comprises four plates each having a portion with a longitudinal channel therein and an unchanneled or a longitudinally ,channelled portion at right angles to saidV Iirst mentioned portion so that when said four plates are assembled with said right angled portions' together two-and-two and said first mentionedportions together' two-and-two an anode is formed which in'section is in the form of a cross with a longitudinal tunnel in theopposite arms thereof inthe one case and inall the four arms in the other case; f.

To enable the invention to be clearly' understood it will now be described with reference to the accompanying drawings in which Fig. 1 is an end viewof one form of anodev in accordance with the invention and Fig. 2, a perspective view thereof. Figs. 3, et, 5 and 6 'are end views of four other different forms of theanode.

Referring` to Figs. `1 and2 the anode therein illustrated comprises two exactly similar sheet= metal platesl and 2, the length of which is several times greater than the width vthereof as clearly shown-in Fig. 2. Eachplate is formed by pressingror other semicircular 3,

Vtending longitudinally of the plate in the centre thereof as clearly shown, whereby when the plates are superposed on one another' a cylindrical tunnel 4 is formed through which a iilamentary or other form of cathode is adapted to be located.

The plates 1 and 2 .may be provided with a plurality of channels 3 to provide when the plates are superposed on one another with a corresponding number of cylindrical tunnels 4. Thus in Fig. 3 each plate is provided with two channels 3 whereby there are two tunnels 4. In Fig. 4 each plate is formed'with four channels 8 providing four tunnels 4.

In Fig. 5 the anode comprises four exactly similar plates 5, 6, 7 and 8. Each plat-e comprises a portion having a longitudinal. channel 3 therein and an unchannelled portion 9 at right angles to the channelled portion so that when the four plates 5, 6, 7 and 8 are assembled with said unchannelled portions together two-and-two, and said channel portions together twoeand-two, an anode is provided which in section is of the form of a cross with a longitudinal tunnel 4 1n opposite arms thereof. In a modification of the arrangement shown in Fig. 5 each of the portions 5, 6,7 and 8 may be provided with a longitudinal channel 3 whereby there will be when the plates are assembled a tunnel4 in each arm of the cross as clearly shown in Fig. 6.

The two or more metal plates constituting the anode may be secured together by welding, riveting or stapling. In Fig. 2V the sheets 1 and 2 are secured together by means of staples indicated at 9.

A An anode constructed in accordance with the invention may be supported along with the cathode, with or without a grid, upon a framework which is comprised for example of a plurality of parallel stem members, for example two stem members,I which are held together andr spaced apart by means of cross piecesv as described inthe specification of co-pending application Serial No. 722,811, filed 27th J une, 1924, previously referred to. As described in said specification the stems may be constructed of insulating material such as silica, steatite or glass in which case they are preferably of a heat resistingrglass, or the stems may be wholly or in part metallic, suitable insulating breaks being provided in order to insulate thevvarious electrodes or electrode supports. Metallic cross-pieces lit on the stems and are provided with holes, recesses, projections or other suitable means for registering and holding the electrodes which they support. The ycross pieces are arranged toV i'it into `or on to the stems so that no adjustment is required inassembling the electrodes. By this means the electrodes are constrained in the direction of their length. Furthermore,

means are provided that while the electrodes are constrained in the direction of their length, the electrodes are able to expand or contract in this direction. For this purpose one or more of the supporting cross pieces maybe flexible or elastic or the electrodes may be slidably mounted within the registering cross pieces or one or more of the cross pieces may be slida ly mounted on the supporting framework. If desired the electrodes may be held in tension. For example in a three electrode tube the grid may be held in tension. When the grid vis comprised ef a helix or assemblage of wires which :in itself is not rigid then it is preferably arranged that the grid is supported by a rigid member. It may be lashed or welded thereto and the rigid member in turn supported and constrained by the cross pieces.

The filament is of hair-pin formation comprising a pair of parallel wires as described in the specification of co-pending application Serial No. 745,194 filed 22nd October, 1924. Such `filament is supported in the manner described in the specification of copending application Serial No. 717,827 filed 2nd June, 1924. The anode. comprises two similar sheets of molybdenum or nickel for 4example which are pressed er stamped so that each has two channels as shown in Fig. 3.y The two channel sheets are fixed together by welding, riveting or stapling so that two tunnels are provided by the channels, the inner surfaces of which constitute the active surfaces of the anode. The anode thus constructed is supported in cross-pieces aiixed to the abovermentioned glass side stems of the supporting framework and each crosspiece consists of a metal strip having a cir cular perforation at each end thereof, through which passes a glass stem,y of the framework, said strip being alsoprovided with a rectangular slotv with ya pair of circular enlargements, the shape of the enlargements corresponding with the external con.- tour of the channels of the anode just above described. Three of such supporting strips may be provided for example, the anode passing through the Yslots therein. One of the strips may be of channel sectionin order that it may be rigid'whilst the other strips possess flexibility to permit expansionof the anode and the anode maybe securedto said channel section cross-piece. Thel crosspieces may be of nickel or where the valve is operated at a high temperature such as during evacuation of the tube for expelling occluded gas, they may be ofmolybdenum or certain yof the cross-pieces may be of nickel for example those at the ends of the anode and others of molybdenum, for example those aty the central part of the anode.

A more complete description of the conof the references to the prior specifications.

YVith the construction above described the anode will be definitely registered with respect to the filament wires and may be easily and ei'fectively assembled sogas to provide a short gap between the i'ilament and the anode. In a three-electrode valve a grid may be supported from cross-pieces on the framework in a manner similar to that described in connection with the anode.

The anode may be slidably mounted on the cross-pieces but it is preferably fixed to the rigid cross-piece for example by means of a wire welded bot-h to the cross-piece and the anode or the latter may be provided with tongues o r projections which may be bent out so that it is locked in position upon the supporting cross-piece or pieces. The flexile cross-pieces may be iixed to the glass stems oi' the framework by wire binding or in other convenient manner.

From the iorgoing description it will be seen. that the inter-electrode gap may be easily made small wit-hout the liability of the electrodes touching one another even when a iilamentary cathode and high volt" ages are employed in the tube. rilhe discharge may easily be contined to the inter'- electrodes space by virtue of the cool ends oi the iilament or alternatively shields may be employed. Thus the invention provides a simple and effective yassembly whereby a vacuum tube may be constructed of low impedance, owing to the small spacing of the electrodes, or operated at high voltage in a comparatively high gas pressure with trodes herein described since the Yframework may assume other -forms and the anode may be supported thereon in different ways. Moreover the electrodes need not bemounted upon a distinct framework but may be supported in other ways such as by means of stems projecting from a glass pinch or seal.

`We claim as our invention In a vacuumtube, an anode comprising a 1 ,C plurality oi members oi sheet metal, each member comprising an angular portion, a plurality voi flat portions and a plurality oi semi-cylindrical portions separated by said fiat and angular portions and similarly placed in the several members and all saidl portions in any one member being concave toward the same V'face of the .member and the members being assembled with said faces toward each other, the angular' portions adjacent each other, and vthe semi-cylindricalv portions in registeia whereby cylindrical spaces for the cathode are provided.

ln testimony whereof we have hereunto subscribed our names this 7th day of April,

ERNEST YEOIVIAN ROBINSON. EDWARD .lOl-IN EGERTON HUBBRD. 

